If you work with native mode assemblies that include components with compressed midsurface shells, Creo Simulate determines which components are modeled with midsurfaces. For these components, the software creates automatic midsurface connections wherever surfaces mate or overlap with those of another component. Creo Simulate makes an exception for those surfaces that you explicitly designate as free interfaces or those in contact through a weld, fastener, or rigid link. FEM mode does not support automatic midsurface connections.

Automatic midsurface connections allow the mated areas of the assembly to deform as if they were one body. When you mesh your model, these connections appear as dotted magenta lines along the edges of all connected curves and surfaces.

In general, you should only use automatic midsurface connections if the area of contact is small relative to the size of the model. Also, for certain models, Creo Simulate can give results that do not reflect the actual displacement if you use automatic midsurface connections. When you select the default interface type as Free, Creo Simulate does not create bonding elements by default.